Francisco Machado of Lowell had long gone without health insurance. Strong and healthy, he preferred to save the money or send it to family in Brazil, until pain and buzzing in his ear sent him to the emergency room. The $600 bill persuaded him to enroll in a plan offered by his employer, a cleaning company.

Having coverage meant that the 45-year-old would no longer be hit with a state fine — he paid $406 in 2011 — for being uninsured. But this spring Machado moved to a part-time job and became uninsured again.